Messages in this thread | | | Subject | Re: [PATCH v1 2/2] drivers/gpu/drm: don't select DMA_CMA or CMA from aspeed or etnaviv | From | David Hildenbrand <> | Date | Thu, 8 Apr 2021 12:27:02 +0200 |
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On 08.04.21 12:20, Arnd Bergmann wrote: > On Thu, Apr 8, 2021 at 11:22 AM David Hildenbrand <david@redhat.com> wrote: >> >> Random drivers should not override a user configuration of core knobs >> (e.g., CONFIG_DMA_CMA=n). Use "imply" instead, to still respect >> dependencies and manual overrides. >> >> "This is similar to "select" as it enforces a lower limit on another >> symbol except that the "implied" symbol's value may still be set to n >> from a direct dependency or with a visible prompt." >> >> Implying DRM_CMA should be sufficient, as that depends on CMA. >> >> Note: If this is a real dependency, we should use "depends on DMA_CMA" >> instead - but I assume the driver can work without CMA just fine -- >> esp. when we wouldn't have HAVE_DMA_CONTIGUOUS right now. > > 'imply' is almost never the right solution, and it tends to cause more > problems than it solves.
I thought that was the case with "select" :)
> > In particular, it does not prevent a configuration with 'DRM_CMA=m'
I assume you meant "DRM_CMA=n" ? DRM_CMA cannot be built as a module.
> and 'DRMA_ASPEED_GFX=y', or any build failures from such > a configuration.
I don't follow. "DRM_CMA=n" and 'DRMA_ASPEED_GFX=y' is supposed to work just fine (e.g., without HAVE_DMA_CONTIGUOUS) or what am I missing?
> > If you want this kind of soft dependency, you need > 'depends on DRM_CMA || !DRM_CMA'.
Seriously? I think the point of imply is "please enable if possible and not prevented by someone else". Your example looks more like a NOP - no? Or will it have the same effect?
-- Thanks,
David / dhildenb
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